Methods of improving the durability of glass containers



Patented Oct. 31, 1950 T" OFFICE METHODS OF IMPROVING THEDURABILITY OFGLASS CONTAINERS Eric Sedd'on, London, England No Drawing. ApplicationApril 27, 1948, Serial N 0. 23,627. In Great Britain'January 25, 1943 3Claims. 1

conditions which commonly. cause some deterioration in the quality orappearance of glass surfaces.

It is known to treat the interior surfaces of glass containers byexposing them, whilst hot,

to the action of acidic gas. For this purpose, it has been proposed todeposit in the glassware While the latter is hot, a sulphur pellet whichwhen subjected to the heat of the glassware, fires and liberates anacidic gas. It has also been proposed to pass the bottles through amuflle or annealing lehr that is charged with an acid gas.

In accordance with the present invention, there is provided a method ofimproving the durability of, glass bottles and like containers whichcomprises introducing into the container a mixture of ammonium saltscontaining both sulphur and oxygen, with halogen salts of the ammoniumradicle NH4 such as ammonium chloride. In this way, a more completeremoval of alkali at or immediately beneath the internal surface of theglassware is facilitated.

The ammonium salts containing both sulphur and oxygen may consist ofammonium sulphate,

or ammonium bisulphate, or ammonium thiosulphate, or ammoniumpersulphate, either alone or combined as regards any of them with aretarding agent, such as, for example, ammonium carbonate or ammoniumbicarbonate.

In carrying the invention into effect, the materials may be introducedinto the containers in tabletted, briquetted or pelleted form or ascrystals or powders. Alternatively, they may be introduced as a sprayafter dissolving in suitable solvents, or in vapour form aftervolatilising the medium at suitably chosen tempeartures in an externalapparatus.

The materials used may be introduced into the hot glassware passingmechanically or by hand from the glass forming machines to the .moniumchloride.

2 1 annealing lehr, or, alternatively, they may be introduced into coldglassware entering the oven or mufile lehr such as is used forre-heating, reannealing or enamelling.

In the preferred mode of carrying out the invention, the necessaryamount of the mixture in tabletted, briquetted, or pelleted form, isintroduced into the hot bottle or container by automatic means as itpasses on a conveyor or the like from the forming machine to theannealing lehr. It is to be understood, however, that the mixture, neednot necessarily be in briquetted or pelleted form, but may, in someinstances, be introduced into the bottle in the form of crystals orpowder, or it may be dissolved or suspended in a volatile liquid, e. g.water, which is introduced into the bottle by means of a sprayingnozzle, tap, or other well-known means, or it may be introduced by otherthan automatic means, as, for instance, manually, nor is it necessary tointroduce the substance into the bottle while the latter is hot. It may,for instance, be convenient to introduce the substance into the bottlewhile it is cold and then to reheat the bottle in a more or less closedmuflle to a temperature sumcient to decompose the mixture and sufiicientto cause the resulting acid gases to react with the hot glass surface.

I have found that ammonium chloride is by no means so satisfactory asammonium sulphate as it does not produce such high durability.Consequently the proportion of ammonium chloride in the mixture shouldbe less than the sulphate. Some chloride is however desirable and inparticular it serves as a binder to enable the mixture to besatisfactorily pelleted. I prefer therefore a mixture consisting of90-97 per cent of ammonium sulphate, the remainder being am- A trace ofa Wax serving as a pelleting lubricant may also be included, e. g. 0.2per cent or less than 0.5 per cent. The wax may be stearic acid.

I claim: 1

l. A method of improving the durability of glass containers whichcomprises introducing a pelleted mixture of ammonium sulphate withammonium chloride into the container and effecting a decompositiontherein of said mixture, the mixture containing 90 to 97 per cent ofammonium sulphate.

2. A method of improving the durability of glass containers whichcomprises introducing a pelleted mixture of ammonium sulphate withammonium chloride into the container and effecting a decompositiontherein of said mixture, the quantity of ammonium sulphate in themixture being greater than the quantity of ammonium chloride.

3. A method of improving the durability of glass containers whichcomprises introducing a pelleted mixture of ammonium sulphate withammonium chloride and a lubricant into the container and effecting adecomposition therein of said mixture, the mixture containing 90 to 97per cent of ammonium sulphate and less than 0.5 per cent of a lubricant.

ERIC SEDDON.

A REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,760,427 Matlock May 27, 19302,053,066 Cunningham Sept. 1, 1936 2,081,401 Kniskern May 25, 19372,175,076 Burch Oct. 3, 1939 2,184,320 Simpson Dec. 26, 1939 2,436,771Hood Feb. 24, 1948

1. A METHOD OF IMPROVING THE DURABILITY OF GLASS CONTAINERS WHICHCOMPRISES INTRODUCING A PELLETED MIXTURE OF AMMONIUM SULPHATE WITHAMMONIUM CHLORIDE INTO THE CONTAINER AND EFFECTING A DECOMPOSITIONTHEREIN OF SAID MIXTURE, THE MIXTURE CONTAINING 90 TO 97 PER CENT OFAMMONIUM SULPHATE.